Field of the Invention
The present invention relates to an optional device for an electrical machine and to an electrical machine.
Discussion of the Background
Electrical machines such as image forming apparatuses emit exhaust gases that contain ultrafine particles (UFPs) of siloxane, which results from heating of silicon, or hydrocarbon, which results from melting of toner at high temperatures. In recent years, stricter regulations have been imposed on ultrafine particles. This requires the electrical machines to use a filter or a similar device to collect ultrafine particles in the exhaust gas and to discharge purified air to the atmosphere. Newly developed electrical machines are designed to satisfy this requirement against ultrafine particles in the exhaust gas. In order for existing electrical machines to satisfy the requirement, a discrete, optional device that has a function to purify the exhaust gas may be added to the existing electrical machines.
Japanese Patent No. 4812885 discloses an air purifier for use in vehicles. The air purifier is a discrete optional device. The air purifier includes a rechargeable built-in power source, and detects the presence or absence of power feeding from the power source of the vehicle. Depending on whether power is being fed or no power is being fed, the air purifier performs control to change the wind force of the ventilator of the air purifier.
When an optional device is for an image forming apparatus or some other electrical machine connected to a commercial power source, the optional device can be powered directly by the commercial power source, instead of by the electrical machine. It is necessary, however, to electrically connect the electrical machine and the optional device to each other in order for the electrical machine to send the optional device electrical signals to control operation of the optional device.
In an exemplary case of an image forming apparatus, while the image forming apparatus is in waiting mode, an exhaust gas fan is out of operation or rotating at speeds so low that the amount of exhaust gas is negligibly small. Thus, the amount of ultrafine particles in the exhaust gas is negligible. While the image formation unit is in operating mode, the exhaust gas fan is rotating at full speed, emitting a larger amount of exhaust gas, which contains a larger amount of ultrafine particles. This necessitates control that includes sending the optional device an electrical signal to determine whether the image forming apparatus is in waiting mode or operating mode and making the optional device effect its air purification function while the image forming apparatus is in operating mode.
In order to implement the electrical connection, however, it is necessary to provide, in advance, the electrical machine with an interface (such as a connector) to make the electrical connection with the optional device possible. Providing the interface leads to an increase in cost. For an existing electrical machine without such interface, it is necessary to modify the electrical machine so as to retrieve the electrical signal and implement the electrical connection with the optional device.
It is an object of the present invention to provide an optional device for an electrical machine and provide the electrical machine to deal with the above-described circumstances. Specifically, the optional device is discretely mountable to the electrical machine without electrical connection to the electrical machine, and is capable of performing suitable control in accordance with the operation mode of the electrical machine.